As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING INITIAL CLIMB ON GEAR RETRACTION LEFT ENGINE HAD A RECOVERABLE SURGE. (MOMENTARY WITH LOUD BANG) WITH NO VARIANCE IN ENGINE PARAMETERS. FLIGHT DATA RECORDER READ OUT PERFORMED REVEALING ENGINE SUSTAINED A CATEGORY LEVEL 3 SURGE. LT ENGINE REPLACED AS PER MAINTENANCE MANUAL.